INTRODUCTION While biliary cystadenoma and biliary cystadenocarcinoma involving the liver are not uncommon, biliary cystadenocarcinoma of the gall bladder is an extremely rare lesion and can be very difficult to diagnose. CASE PRESENTATION A 50-year-old Indian woman presented with pain and swelling in the right hypochondrium. An ultrasonography revealed a cystic lesion arising from the gallbladder fossa. This lesion was initially managed with aspiration and antibiotics by the treating physician. The patient was referred for surgical management because the abscess was not resolved through conservative treatment. A diagnosis of an infected nonparasitic cyst was made and deroofing of the cyst was performed. A histopathological examination of the excised cyst wall showed cystadenocarcinoma. The patient subsequently underwent a successful surgical excision of the lesion. CONCLUSION Infective lesions of the liver are common in developing countries and are usually managed through aspiration and antibiotics. Cystadenocarcinoma of the gallbladder needs to be considered in the differential diagnosis of cystic lesions arising from the gallbladder fossa. A high index of suspicion and cytological examination from the wall of such complex lesions will help in the timely management of such lesions.